The guard can be seen lowering his arm as he continues to march on. (YouTube)

Video footage of the incident has been released online, showing a woman wearing a yellow dress and sunglasses standing in the path of the soldier. She seemed to be posing for a photo, standing on the wrong side of a roped off area outside the castle, blocking the soldier's path as he marches in formation.

He barges into her and the woman screams as she is shoved out of the way.

The soldier continues to march on.

The Queen's Guard on duty during President Trump's recent visit. (Getty)

The traditional role of the Queen's Guard is to protect the royal family while they are in residence. They wear distinctive uniforms of red tunics and bearskin hats and have a reputation for being focused at all times on the job at hand.

The Guard has been in existence for the past 350 years.

There are thought to be guidelines in place for guardsmen to deal with tourists trying to distract them. Raising a rifle is considered a 'final warning' is such situations, after which the person is allowed to be detained.

The Ministry of Defence has responded to news of the incident telling The Sun, "The Household Division is proud to guard Her Majesty and honoured that people come from around the world to watch our ceremonial spectacle.

"The ropes are there to protect both the public and our soldiers; please stand behind them."